/**
 * Copyright (c) 2011-2023, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.jfinal.template.expr.ast;

import java.util.AbstractList;
import com.jfinal.template.TemplateException;
import com.jfinal.template.stat.Location;
import com.jfinal.template.stat.ParseException;
import com.jfinal.template.stat.Scope;

/**
 * RangeArray : [expr .. expr]
 * 
 * 用法：
 * 1：[1..3]
 * 2：[3..1]
 */
public class RangeArray extends Expr {

    private Expr start;
    private Expr end;

    /**
     * array : '[' exprList ? | range ? ']'
     * exprList : expr (',' expr)*
     * range : expr .. expr
     */
    public RangeArray(Expr start, Expr end, Location location) {
        if (start == null) {
            throw new ParseException("The start value of range array can not be blank", location);
        }
        if (end == null) {
            throw new ParseException("The end value of range array can not be blank", location);
        }
        this.start = start;
        this.end = end;
        this.location = location;
    }

    public Object eval(Scope scope) {
        Object startValue = start.eval(scope);
        if ( !(startValue instanceof Integer) ) {
            throw new TemplateException("The start value of range array must be Integer", location);
        }
        Object endValue = end.eval(scope);
        if ( !(endValue instanceof Integer) ) {
            throw new TemplateException("The end value of range array must be Integer", location);
        }

        return new RangeList((Integer)startValue, (Integer)endValue, location);
    }

    public static class RangeList extends AbstractList<Integer> {

        final int start;
        final int size;
        final boolean increase;
        final Location location;

        public RangeList(int start, int end, Location location) {
            this.start = start;
            this.increase = (start <= end);
            this.size = Math.abs(end - start) + 1;
            this.location = location;
        }

        public Integer get(int index) {
            if (index < 0 || index >= size) {
                throw new TemplateException("Index out of bounds. Index: " + index + ", Size: " + size, location);
            }
            return increase ? start + index : start - index;
        }

        public int size() {
            return size;
        }
    }
}




